An Outbreak of Salmonellosis Occurred After an Epidemiology Department Luncheon

An outbreak of salmonellosis occurred after an epidemiology department luncheon, which was attended by 485 faculty and staff. Assume everyone ate the same food items. Sixty-five people had fever and diarrhea; five of these people were severely affected. Subsequent laboratory tests on everyone who attended the luncheon revealed an additional 72 cases. The virulence of salmonellosis was:

A) 13.4%.
B) 47.4%.
C) 28.2%.
D) 7.7%.
E) 3.6%.